德國蜚蠊之嗅覺行為與核心時鐘基因的關係

The Relationship Between the Core Clock Genes and Olfactory Behavior of the German Cockroach, Blattella germanica

林志穎(Chih-Yin Lin)

指導教授 ： 李後晶

國立臺灣大學/生物資源暨農學院/昆蟲學研究所/碩士(2017年)

https://doi.org/10.6342/NTU201704143

摘要

德國蜚蠊在台灣是一種重要的居家害蟲，過去的研究已經證明，在牠們的各種生理及行為上表現日週律動。在果蠅，日週時鐘的機制，已經從個體到分子層級有深入研究，然而在德國蜚蠊中仍舊十分欠缺研究。藉由氣味行為偏好實驗，監測雄性德國蜚蠊成蟲於光暗、全暗以及全亮的環境中對於聚集費洛蒙氣味的行為偏好，結果顯示，在不同環境下，超過80%的德國蜚蠊偏好聚集費洛蒙的氣味，且偏好不隨時間而改變；然而，判斷速度僅在全暗的環境中表現自由律動，光暗及全亮的環境中則沒有顯著差異，這可能是由於德國蜚蠊的躲避行為或受到視覺的刺激所造成的遮蔽效應。接著於全暗環境中，以注射dsper、dstim、dscry2或dsClk＋dscyc的雄性德國蜚蠊成蟲進行實驗，結果顯示，注射dsper之德國蜚蠊，其per的mRNA表現量無法被降低，dstim、dscry2、dsClk或dscyc則皆能被降低；而所有的時鐘基因皆不影響氣味偏好；dsper或dscry2處理之德國蜚蠊則未表現對於氣味判斷速度的日夜變化，顯示其生物時鐘可能無法正常運作。dstim或dsClk＋dscyc處理之德國蜚蠊判斷速度與對照組相同，維持其夜行性之天性，然而CLK/CYC異源二聚體在日週時鐘中扮演著重要角色，若Clk與cyc基因表現量降低時，受日週時鐘所控制的行為應該消失，但結果卻顯示其行為沒有消失，這可能說明RNA干擾技術，在費洛蒙氣味偏好實驗中，是存在限制與不足。

關鍵字

德國蜚蠊 (Blattella germanica) ； 日週律動 ； 時鐘基因 ； 聚集費洛蒙 ； 嗅覺偏好 ； RNA干擾

並列摘要

The German cockroach, Blattella germanica, is one of important household pests in Taiwan. Previous studies have been demonstrated that rhythmic expression of various behaviors. In Drosophila, circadian clock mechanism has been extensively studied from individual to molecular level. However, there are few studies in the German cockroach. The behavioral preference on aggregation pheromone monitors odor preference of male adult German cockroaches under LD, DD or LL condition. The result implied over 80% of individuals prefers aggregation pheromone and maintained at every time point of 24 hours. The time spent to make choice on aggregation pheromone performs free-running rhythm under DD condition. However, there is no rhythmicity under LD or LL condition. The light avoiding behavior or combining visual and olfactory stimulation should speed up the behavioral preference which caused a masking effect on its circadian oscillation under lighting condition. Furthermore, circadian regulation of the odor preference was demonstrated by injecting dsper, dstim, dscry2 or dsClk＋dscyc under DD condition. Although the expression of per was not knocked-down by dsRNA injection, the expression of tim, cry2, Clk or cyc did show significantly reduced. The silencing effect of clock genes did not affect the preference on aggregation pheromone. In addition, dsper or dscry2 injected cockroaches did not show changes on aggregation pheromone choice. The result implied that the circadian clock was not working properly. The time spent to make choice on aggregation pheromone was reflecting the nocturnal nature of the German cockroach when dstim or dsClk + dscyc was injected. Although the transcription factor in feedback loop of circadian clock, Clk and cyc, was knocked-down, the rhythmic behavior of odor preference was not demolished. Therefore, the implantation of RNAi technique on circadian regulation of odor preference has its limitation and deficiency.

並列關鍵字

The German cockroach (Blattella germanica) ； Circadian rhythm ； Clock gene(s) ； Aggregation pheromone ； Odor preference ； RNA interference

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